This application claims the benefit of Korean Application No. 2000-57512, filed Sep. 29, 2000, in the Korean Industrial Property Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to an ink-jet printer head, and more particularly, to a thermal ink-jet printer head of an upward ejecting type and which has improved on the construction of an ink channel so that the area occupied by a unit nozzle can be reduced and an ejected ink droplet can be stabilized.
2. Description of Related Art
An ink ejecting method applied to an ink-jet printer head is generally classified into a thermal driving method and a piezoelectric driving method. In the thermal driving method, ink is instantaneously heated by a resistance heating element, thereby generating and expanding a bubble, and is ejected through a nozzle by the pressure of the bubble. In the piezoelectric driving method, ink is ejected through the nozzle by the pressure generated by the displacement of a piezoelectric element.
Further, the ink-jet printer head of the thermal driving method is classified into a side ejecting type of FIG. 1 and an upward ejecting type of FIG. 2 according to an ink ejecting direction with respect to a base plate and a nozzle plate.
An ink-jet printer head 21 of the side ejecting type as shown in FIG. 1 comprises an ink channel 23, a nozzle 26 formed at one end of the ink channel 23, and a resistance heating element 2 for instantaneously heating the ink in the ink channel 23 to generate and expand a bubble 22, wherein an ink droplet 29 around the nozzle 26 is ejected by the pressure of the bubble 22.
The ink-jet printer head of the upward ejecting type as shown in FIG. 2, comprises a nozzle 36, an ink chamber 39, an ink channel 34 disposed at a side of the ink chamber 39 for supplying ink therethrough, and a resistance heating element 2 for heating the ink in the ink chamber 39 to generate and expand a bubble, wherein an ink droplet is ejected through the nozzle 36 by the expansion pressure of the bubble generated and expanded in the ink chamber 39.
The aforementioned conventional ink-jet printer head, however, has shortcomings of the so-called back-flow of ink, which means that ink flows back into the inner side of the ink channel 23 or 34 due to the expansion pressure of the bubble generated when ejecting ink. The back-flow causes a cross-talk during a printing process, and thus causes a deteriorated print quality.
To solve the problem as described above, the conventional side ejecting type has an elongated ink channel 23 and a protective barrier 24 made of a polymer or the like, which is disposed above a heat driving section including the resistance heating element 2, for preventing the back-flow of ink. However, in the construction as described above, since a unit nozzle occupies a broad area of the base plate, it is required for the ink-jet printer head to be lengthened accordingly, and thus the manufacturing process thereof is complicated.
The conventional upward ejecting type as shown in FIG. 2 has a protruding portion 37 with a neck formed on the ink channel 34 connected to the ink chamber 39, thereby preventing the back-flow of ink. However, due to a complicated manufacturing process and structure, the manufacturing becomes difficult.
Meanwhile, an ink manifold of the conventional ink-jet printer head is formed by wet etching, and the ink channel thereof is formed by laser ablation.
The problem is that the laser ablation deteriorates a quality of the treated surface. Also, the wet etching has problems such as a long treating time, use of chemicals that causes environmental problems, and imprecise treatment.
In order to improve the ink-jet printer head as described above, an object of the present invention is to provide an upward ejecting type of a thermal ink-jet printer head capable of reducing an area occupied by a unit nozzle, and thus enhancing a printing speed and a print resolution by improving a structure of an ink channel.
Another object of the present invention is to provide an upward ejecting type of a thermal ink-jet printer head capable of stabilizing an ejected ink droplet, and thus enhancing a printing efficiency by improving a structure of an ink channel.
Additional objects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
To achieve the above and other objects, an ink-jet printer head in accordance with the present invention includes a base plate having ink channels penetrating therethrough, a donut shaped heat driving section formed in the base plate and encircling an exit of the ink channels, an ink chamber barrier stacked on the base plate for serving as a side wall of an ink chamber, and a nozzle plate stacked on the ink chamber barrier and having a nozzle for ejecting out the ink in the ink chamber.
Here, preferably, the base plate, the ink channels, the ink chamber, and the heat driving section are symmetrical with respect to a shared axis thereof.
The ink channels include an ink manifold formed by hollowing the lower portion of the base plate to have a predetermined area therein and an ink supplying path formed by being hollowed to have a narrower area therein than that of the ink manifold, which connects the ink manifold with the ink chamber.